Bc excitations at LHC: first observations and further research prospects

A V Berezhnoy,I N Belov,A K Likhoded,A V Luchinsky

doi:10.1051/epjconf/201922202009

Abstract

Status of the Bc meson excitatons search is presented in our work. We discuss the 2S Bc states first discovered by ATLAS and newly confirmed by CMS and LHCb collaborations. We review the observation prospects for the rest predicted states (B∗c, 2P wave, 3P wave and D wave) at LHC experiments. Cascade decays to the ground state as well as direct decays to the lepton pair are regarded for these states.

Highlights

Bc-meson is a nonrelativistic two heavy quark system
This cbstate is well studied by the LHC Collaborations LHCb, CMS, ATLAS in numeral decay modes [9]
We discuss the latest results of LHC Collaborations CMS, ATLAS and LHCb, independently observed 2S excitations of Bc meson

Summary

Introduction

Bc-meson is a nonrelativistic two heavy quark system. The potential model framework in analogy with (bb) and (cc) states predicts 19 bounded states for (cb) below the decay threshold to BD (see [1,2,3,4]). For the first time the ground state of Bc-meson was observed at Tevatron (CDF and D0 experiments) in two decay modes: Bc → Jψlν (l = e, μ) and Bc → Jψπ [5,6,7,8] This cbstate is well studied by the LHC Collaborations LHCb, CMS, ATLAS in numeral decay modes [9]. According this study the Bc-meson production at fixed gluon interaction energy resolves itself to just a b-quark fragmentation (like fragmentation b → B) only at high transverse momenta, where the cross section ratio between the production of vector state B∗c and pseudoscalar state is predicted to be RBc ∼ 1.4 1. It is worth noting that the sharp change of this value is not expected within the conventional production model

Radiative Bc meson decays

33 P2 final state

D-wave excitations at LHC

Lepton pair production in radiative Bc meson decays

Findings

Conclusion